Septage

Septage or septic tank sludge refers to the partially treated sludge stored in a septic tank or (less commonly) in a pit latrine. It is one type of fecal sludge. Septage is a by-product from the pretreatment of household wastewater in a septic tank where it accumulates over time. Septage is pumped out of a septic tank or onsite sewage facility with a vacuum truck. The septic tanks can be residential or non-residential. Non-residential sources can include wastewater from commercial/industrial development, grease interceptor as well as other sources such as portable toilet, RV, and boat waste.

Historically, the term "night soil" was used for fecal sludge and can still be found in some current publications.

Another definition of septage is: "A historical term to define sludge removed from septic tanks." The term "historic" is used because it is nowadays often replaced by the term "fecal sludge" (or faecal sludge in British English), even though "fecal sludge" may have a negative connotation associated with it because it contains the word "feces".

Septic tank sludge or septage is in fact a specific type of "fecal sludge" - a term nowadays widely used in the context of developing countries. Fecal sludge includes the fecal sludge or septage from septic tanks as well as fecal sludge from pit latrines or from public toilets that are not connected to a sewer. Fecal sludge management is a challenge for many cities in developing countries where a large fraction of the population is using on-site sanitation systems. Fecal sludge needs to be managed safely.

Septage is limited to septic tank contents whereas fecal sludge includes contents from other on-site sanitation technologies as well, not only from septic tanks. The term "septic" in septage implies that the sludge has gone through some anaerobic biological degradation and thus is at least partly stabilised. Fecal sludge on the other hand is a wider term and also includes "fresh" sludges from non-sewered public toilets.

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